Himanshu Shah Ping Pan Ciena Corp PWE3 Working Group Internet Draft Hamid Ould-Brahim Nortel Networks April 2004 Chris Metz Expires: October 2004 Cisco Systems Qos Signaling for PW draft-shah-pwe3-pw-qos-signaling-00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document discusses how a tail-end PE can signal the Quality of Service parameters of the local Attachment Circuit to the head-end PE for appropriate Pseudowire generation from head to tail end PE. The Pseudowires traditionally provide connectivity between two Attachment Circuits that are on the edges of a service providerÆs network. A service provider assigns specific QOS parameters to these Attachment Circuits based on the service sold to the customer. In order to interconnect and maintain the same level of service Shah, et al. Expires August 2004 1 Internet Draft draft-shah-pwe3-PW-Qos-Signaling-00.txt parameters across the service provider network, it is prudent that the Provider Edge devices that are endpoints of the Pseudowires, select or create a suitable transport path that meets the PseudowireÆs quality of service requirements. It is also possible that a PE may use appropriate policing for traffic entering Pseudowire that match remote Attachment CircuitÆs capabilities. In order to accomplish an integrated service delivery it becomes necessary that each PE understand the QOS requirements of the remote Attachment Circuit. This draft proposes an extension to the PWE3 control signaling to enable a PE to exchange QOS parameters of the local Attachment Circuit at the time of the PW establishment. 1.0 Specification of Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119. 2.0 Introduction The [PWE3-CONTROL] draft describes how two PEs signal PW-FEC to each other in order to establish a pseudowire. The PW-FEC is exchanged over the targeted LDP session and contains Pseudowire signaling information that includes interface parameters of the local Attachment Circuit. This draft describes a mechanism whereby additional information, such as QOS parameters of the local Attachment Circuit can be dispatched with the VC-FEC in a backward compatible fashion. This document specifies QOS TLV that can be included in the initial Label Mapping Message and subsequently in LDP notification message for conveying up-to-date information about the Pseudowire. This proposal is orthogonal to the type of PW-FEC used. Both PWid FEC and Generalized ID FEC can make use of the new additions. In the case of PWid FEC the signaled QOS information can be related to the GROUP_ID value when this field is used in signaling. It is expected that capability of exchanging QOS information dynamically would facilitate various applications to optimize the use of core resources effectively. For example, a PE may use this signaling for backpressure when æforward congestionÆ is detected on its local AC. 3.0 Capability Learning for QOS exchange For the purpose of learning remote end capabilities and for the purpose of signaling to the remote end the local capabilities, this draft suggests that the QOS TLV be included initially in the Label Shah, et al. Expires October 2004 2 Internet Draft draft-shah-pwe3-PW-Qos-Signaling-00.txt Mapping message and particularly in the Optional Parameter field of Label Mapping Message. When subsequent updates are required (after the PW is established), the sender PE will use the LDP notification message to convey an update of the new information. Note that the mechanism described in this draft allows a given PE that does not support the QOS TLV to be able to establish a Pseudowire using normal operations. Indeed, the PEs that are upgraded with such new functionality, examine the optional parameters and note QOS TLV to learn the capability of the sending peer. The sender must include the QOS TLV that it intends to use later as an update, in the Label Mapping message that is used to setup the FIB. Typically, such Label Mapping message is either the first Label Mapping message or the one right after the Label Withdraw/Release message and is referred to in this document as a ôLearning Label Mappingö message. The absence of a given TLV in the Learning Label Mapping message indicates to the receiver that the sending PE is either not capable of processing such TLV or does not wish to engage in dynamic update exchange for that TLV. The absence of QOS TLV indicates to the receiving PE that normal PW signaling procedures should be used to establish the PW (i.e., no inclusion of the optional TLVs in the reverse label mapping). Similarly, the receiving PE that has not been upgraded with the new TLVs and receives a label mapping with the new TLVs will just ignore these TLVs during label mapping processing phase. The capability learning aspect of the PW QOS is only applicable for the use of QOS TLV for dynamic update notifications. It does not change the need to send the initial QOS TLV, irrespective of whether remote PE is capable of processing the optional TLV or not. It is also possible that the receiving PE is capable of processing QOS TLV and uses unacceptable QOS requirement as a criterion to release the VC-FEC. In such event, a status TLV is defined to be included in the optional parameter field of the label release message that informs the remote PE about the reasons for the rejection. 4.0 Pseudowire QOS TLV The pseudowire QOS TLV is used to notify the remote PE about Quality of Service requirements of the local Attachment Circuit. As stated earlier, this information can also be passed as an update. It is possible that receiver may either adjust QOS parameters of the existing tunnel or may respond to the update by first withdrawing the advertised PW label and re-advertise new PW label with same VC- FEC. Shah, et al. Expires October 2004 3 Internet Draft draft-shah-pwe3-PW-Qos-Signaling-00.txt 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|0| PW QOS TLV (TBD) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Committed Information Rate (CIR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peak Information Rate (PIR) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Committed Burst Size (CBS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peak Burst Size (PBS) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Number of Sub-TLVs | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sub-TLVs (1-n) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Traffic Engineering Parameters Each TE parameter is encoded as a 32-bit IEEE single precision floating-point number. The CIR and PIR are in units of bytes per second while CBS and PBS are in units of bytes. Number of Sub-TLVs This field identifies the number of Sub-TLVs that follow. In absence of any Sub-TLVs, this field should be set to zero. This field is mandatory. Reserved This field is set to zero. Sub-TLVs (1-n) The n number of Type-Length-Value fields where ænÆ is equal to æNumber of Sub-TLVsÆ field. The presence of field facilitates future/proprietary extensions 5.0 New LDP Status Codes The PW Status TLV described in this document is the status code point that may be used by the receiving PE to inform the sender the specific reasons for not accepting the Label Mapping message. The status TLV should be included in the æoptional parameterÆ field of the Label Release message. Shah, et al. Expires October 2004 4 Internet Draft draft-shah-pwe3-PW-Qos-Signaling-00.txt The format of the PW Status TLV is: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|0| PW Status (0x096A) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Where the status code is a 4 octet bit field is specified in the PW IANA Allocations document [13]. According to Section 4.4 in RFC3036, we can define new status codes in the range of 0x20000000-0x3effffff. Here are the new status codes: - 0x20000003 "TC is OK" - 0x20000004 "Cannot accept the TC parameters" - 0x20000005 "Preempted due to TC processing" 6.0 General Procedures The PW QOS TLV is included in the Optional Parameter Field of the Label Mapping Message and the LDP Notification Message. In case of Label Mapping Message, Optional Parameter Field follows the Label TLV object. In LDP Notification Message, Optional Parameter Field must include PW-FEC TLV before QOS-TLV. As described above, exchange of QOS TLV in Notification Message is determined by the capability learning during the initial Label Mapping exchange. The PW QOS TLV conveys Quality of Service parameters that advertising PE would like remote PE to consider when selecting/creating appropriate transport tunnel to carry the Pseudowire from remote PE to the advertising PE. The Quality of Service parameters can also be used by the receiving PE to select appropriate policer for his Attached Circuit. The QOS TLV is optional. The received PE uses this information as a suggestion. Note that use of PW QOS exchange helps utilize core resources effectively in the following manner. . Head end PE selects a transport tunnel that best suits remote Attachment CircuitÆs QOS requirement . More PWs can be multiplexed over a transport tunnel . Transport tunnel can be right-sized with various upsize and downsize thresholds Shah, et al. Expires October 2004 5 Internet Draft draft-shah-pwe3-PW-Qos-Signaling-00.txt . Eliminates the wastage of packet forwarding resources in the core when received traffic exceeds the Attachment Circuit QOS criteria at the tail end. 7.0 Security Considerations The security aspects of this solution will be discussed at a later time. 8.0 References [PWE3-CONTROL] Martini et. Al., ôTransport of Layer 2 Frames Over MPLSö, draft-ietf-pwe3-control-protocol-01.txt, August 2002 (work in progress) Acknowledgement Author's Address Himanshu Shah Ciena Corp 35 Nagog Park Acton, MA 01720 Email: hshah@ciena.com Ping Pan Ciena Corp 10480 Ridgeview Court Cupertino, CA 95014 e-mail: ppan@ciena.com phone: +1 408.366.4700 Hamid Ould-Brahim Nortel Networks P O Box 3511 Station C Ottawa, ON K1Y 4H7, Canada Email: hbrahim@nortelnetworks.com Chris Metz Cisco Systems, Inc. 3700 Cisco Way San Jose, Ca. 95134 Email: chmetz@cisco.com Full copyright statement Shah, et al. Expires October 2004 6 Internet Draft draft-shah-pwe3-PW-Qos-Signaling-00.txt Copyright (C) The Internet Society (1999). All Rights Reserved. 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